TURBOMACHINE COMPRESSOR WITH A VARIABLE GEOMETRY INLET BLADE

Abstract

(title) TURBOMACHINE COMPRESSOR WITH A VARIABLE GEOMETRY INLET BLADE Turbomachine compressor, particularly for an aircraft or helicopter, the compressor comprising: an inlet blade (26) having a foot (30) and a head (32), the foot (30) and the head (32) defining a twist of the blade (26); and a blade orientation adjustment mechanism, the compressor being notable in that the blade orientation adjustment mechanism comprises: a first actuator (36), for pivoting the foot (30); and a second actuator (38) for pivoting the head (32), said actuators (36, 38) allowing the orientation of the blade (26) to be adjusted together, and said actuators (36, 38) being configured to be controlled independently of each other in order to vary the twist of the blade (26). (Figure to be published with the abbreviation: Figure 5)

Description

Title of the invention: TURBOMACHINE COMPRESSOR WITH A VARIABLE GEOMETRY INTAKE BLADE technical field

[0001] The invention relates to the field of turbomachinery for aircraft. In particular, the invention focuses on the design of the radial or axial compressor of such a turbomachine. Previous technique

[0002] A compressor generally comprises several successive compression stages through which an airflow passes. At the inlet of these stages may be an annular array of so-called pre-rotation blades which can pivot on their axes to direct the flow and / or reduce its velocity at the compressor inlet. The angular position of the pre-rotation blades can be controlled according to the flight envelope (takeoff, cruise, etc.) and / or according to the engine speed or load. An example is given in document FR 3 019 597 AL

[0003] The blades are assembled to the housing at both ends, root and tip. The blades can be straight, that is, the surface of the blade in contact with the flow is a ruled surface with parallel generatrices. Alternatively, the blades can be twisted, that is, the blade profile is angularly pivoted between the tip and the root (pivoted around an axis substantially parallel to the axis of rotation of a radial compressor, and around a substantially radial axis of an axial compressor).

[0004] The blade twist is sized to provide good efficiency at a given engine operating point. Therefore, the twist is not optimal across the entire range of compressor operating conditions. Consequently, the engine efficiency is not optimal across its entire operating range.

[0005] Another effect that can affect engine performance is the presence of ice on the pre-rotation blades, as the ice alters the blade geometry. Ice can also, when it forms on the blade and then detaches, damage certain turbomachine components. Some technologies exist to prevent ice formation (or to remove it once it has formed).

[0006] One known solution against icing is the integration of electrical resistors into the blades. This requires a certain thickness for the blade and the integration of electrical conductors. The conductors must be small and inserted into twisted cavities. This technique is therefore not mechanically robust in an environment subject to vibrations.

[0007] Another known solution against icing is the injection of hot air drawn downstream at a point in the turbomachine where the air is warmer. This technique is very energy-intensive: it consumes several tens of percent of the rated power. This technique is only effective at high engine speeds, since at low speeds the compressor does not heat the air sufficiently and does not deliver enough flow to eliminate the icing. Thus, this technique is not effective for an aircraft flying at low altitude and at idle, for example during landing, while paradoxically the risk of icing formation is particularly high at low altitudes. Description of the invention

[0008] The present invention aims to provide a compressor that overcomes the aforementioned disadvantages of known compressors, and in particular to provide a compressor that delivers better efficiency over its entire range of use, i.e. at all speeds and at all altitudes.

[0009] The invention relates to an aircraft turbomachine compressor, the compressor comprising: a casing; an inlet blade having a foot and a head, the foot and the head defining a twist of the blade between them; and a mechanism for adjusting the orientation of the blade, the compressor being remarkable in that the mechanism for adjusting the orientation of the blade comprises: a first actuator fixed to the casing, capable of pivoting the foot; and a second actuator fixed to the casing, capable of pivoting the head, said actuators allowing adjustment of the orientation of the blade, and said actuators being configured to be controlled independently of each other in order to vary the twist of the blade.

[0010] The aircraft can be an airplane or a helicopter.

[0011] By twist, we mean an angle (which may be zero) materializing an angular offset between the head and the foot, that is to say a difference between the normal to the blade passing through the foot and the normal to the blade passing through the head.

[0012] The orientation of the blade can be defined by convention as the angular position of the head, or the foot, or any other characteristic point of the blade.

[0013] When the actuators are simultaneously controlled to pivot the head and foot by the same angle (in the same direction of rotation), only the blade orientation is controlled. When the actuators are controlled differently from each other, the twist is controlled. Depending on the convention given to the orientation (see previous paragraph), it can also vary when the two actuators are controlled differently from each other (for example, if the orientation is defined by the angular position of the foot, pivoting the foot without pivoting the head results in a change in twist and orientation).

[0014] It is understood that the blade is sufficiently flexible and / or thin and / or elastic to deform without breaking under the action of the actuators and thus allow variable twisting.

[0015] The blade can be provided with an aerodynamic profile (intrados and extrados).

[0016] The possibility of varying the twist allows for an improvement (more precisely an optimization) of performance at all engine speeds (including partial), which will result in an improvement in the engine's specific consumption.

[0017] The margin at pumping is also reduced thanks to the variable twist of the pre-rotation blades because the twist can be continuously adapted and optimized to the aerodynamic conditions at the inlet of the compressor.

[0018] The arrangement of the actuators at the top and bottom allows for precise blade orientation and twist control. The design is also robust and durable. Imposing a specific orientation at the top and bottom does not restrict the blade material. It can be made of an isotropic and homogeneous material, such as stainless steel, elastomer, etc.

[0019] The advantageous embodiments of the invention contribute to improving the efficiency of the engine over its entire operating range to varying degrees.

[0020] According to an advantageous embodiment, the foot and the head are each formed of a frame and an axle, the frame and the axle being made of a material more rigid than the blade. This robust design allows for precise control of the twist and therefore optimized efficiency at all speeds.

[0021] According to an advantageous embodiment, the reinforcement is a disc preferably embedded in the housing. This advantageous design limits undesirable aerodynamic effects (leaks, turbulence) and also allows for efficient transmission of torsional forces to the blade. A mounting platform can be arranged in the housing, and the reinforcement can be embedded therein.

[0022] According to an advantageous embodiment, at least one of the actuators comprises an electric motor that directly or indirectly pivots the head or the foot. An electric motor (for example, a stepper motor) allows for precise control and sufficient torque to twist even relatively inflexible blades.

[0023] According to an advantageous embodiment, at least one of the actuators comprises a cylinder actuating a ring connected to the foot or the head by a connecting rod. This robust technology, known for variable-angle blades, can here be applied to the foot and the head.

[0024] According to an advantageous embodiment, an electromechanical linear vibrator is arranged in the blade orientation mechanism. The oscillations generated by the vibrator prevent or eliminate the presence of ice on the blade, resulting in improved compressor efficiency under all flight conditions.

[0025] The invention also relates to the use of a compressor according to one of the embodiments described above, the use including a step of varying the twist of the blade by controlling at least one of the two actuators, preferably as a function of the rotation speed of the compressor.

[0026] This allows the twist to be adapted to all flight conditions.

[0027] The twist can be controlled to vary from -10° to +65° relative to the nominal twist (which may or may not be zero).

[0028] The invention also relates to the use of a compressor according to one of the embodiments described above, the use including a step in which at least one of the actuators is controlled to create an oscillatory pivoting of the foot and / or the head of the blade.

[0029] The oscillations prevent the formation of frost, or, if frost is already present on the blade, help to detach it. Indeed, the oscillations weaken the van der Waals forces between the blade (for example, metal) and the ice until they break down, thus causing the expected decohesion of the frost. The geometry of the blade is therefore not affected by frost, thus avoiding performance losses, even in flight conditions conducive to frost formation.

[0030] In an advantageous embodiment, the two actuators are controlled to oscillate the foot and the head: in phase, out of phase, with a phase shift, or at different frequencies; and / or with the same or different angular amplitude; and / or at a fixed or variable frequency, less than 0.5 Hz or greater than 10 Hz, depending on the compressor speed. In an advantageous embodiment, for certain operating conditions, particularly at low speed or idle or below a threshold speed, the oscillations have a large amplitude, for example, about 1°, and a low frequency, for example, less than 0.5 Hz. In an advantageous embodiment, for certain operating conditions, particularly at high speed or above a threshold speed, the oscillations have a small amplitude, for example, about 0.5°, and a high frequency, for example, more than 10 Hz. Preferably, the frequency can be greater than 15 Hz, particularly during acceleration.According to an advantageous embodiment, the oscillations are formed by the superposition of a large amplitude, low-frequency oscillation and a small amplitude, high-frequency oscillation. Thus, the most effective oscillations are imposed across the entire operating range of the engine to ensure the absence of icing and therefore good engine efficiency under all circumstances.

[0031] Thus, the alternating twist between the foot and the head allows for optimized defrosting of the blade at all speeds.

[0032] In addition, oscillations (for example, high frequency) can be superimposed on twist variations to combine the effects of defrosting and flow optimization.

[0033] In summary, the compressor according to the invention and its applications offer a number of technical advantages: precision, reliability, robustness, and durability. The geometry of the pre-orientation blade is optimal under all conditions, in terms of twisting and the absence of frost.

[0034] The consequences also extend to greater operability of the aircraft, whose flight becomes possible in all circumstances, with the safety margin being improved.

[0035] This solution does not present the disadvantages of other known solutions: no reduction in the specific consumption of the engine by drawing in air at a high enthalpy level; and better robustness and durability than electrical resistors integrated into a blade.

[0036] Only a negligible amount of electrical power drawn from the alternator and / or hydraulic power is required, depending on the technology of the actuator envisaged.

[0037] The invention is also versatile in that it accepts a wide variety of possible materials for the blade, and a less restrictive design and manufacture, the actuators being able to "catch up" with a nominal twist which would prove unsuitable during the life of the compressor. Brief description of the drawings

[0038] [Fig.1] is a schematic view of a turbomachine with a radial compressor;

[0039] [Fig.2] shows a blade used in a compressor according to the invention;

[0040] [Fig. 3] shows a blade used in a compressor according to the invention in a twisted configuration;

[0041] [Fig.4] shows a variant with cylindrical armatures;

[0042] [Fig.5] represents the air inlet of a compressor according to the invention. Detailed description

[0043] The figures are represented schematically and some of the dimensions may be exaggerated to facilitate reading.

[0044] In the following description, the terms "internal" and "external" refer to positioning relative to the axis of rotation of the compressor rotor. The axial direction corresponds to the direction along the axis of rotation of the compressor. The radial direction is perpendicular to the axis of rotation. Upstream and downstream refer to the direction of flow within the turbomachine.

[0045] Figure 1 schematically represents a helicopter turbomachine 1. The turbomachine 1 comprises, from upstream to downstream, an air inlet 2, a radial compressor (or centrifugal compressor) 4 equipped with an impeller 6, a rectifier-diffuser 8, an annular combustion chamber 10, a turbine 12 fixed in rotation to the wheel 6 of the compressor 4, a free turbine 14, an outlet diffuser 16 and an exhaust nozzle 18.

[0046] The free turbine 14 comprises a wheel 20 which is rotationally fixed to a drive shaft 22 which extends along the longitudinal axis ZZ of the turbomachine and passes axially through the turbine 12 and the compressor 4. The power from the combustion drives the turbines 12, 14. One 12 drives the wheel 6 in rotation to compress the airflow before it enters the combustion chamber 10. The other turbine 14 drives the drive shaft 22.

[0047] The upstream end of the transmission shaft 22 is located upstream of the air inlet 2 and drives, via a reduction gear 24, a series of accessories (not shown) as well as a power shaft 25 coupled to the helicopter blades.

[0048] Upstream of the impeller 6, the compressor 4 includes an annular row of airflow pre-orientation blades 26 (not shown [Fig. 1]). These blades can be vanes, i.e., be provided with a blade having an aerodynamic profile with an intrados and an extrados.

[0049] Figure 2 describes in more detail a blade 26 of Figure 1. The blade has a body (blade) 28 which is sufficiently thin relative to its length to be torsionally flexible. The blade 26 has a foot 30 and a head 32 at the respective ends of the body 28. The thickness of the body 28 may be identical at every point of the blade, or the thickness may vary from apex to apex and / or from its head to its foot.

[0050] Similarly, the width of the body 28 can be identical from head to foot (as shown) or vary.

[0051] The geometry of the body 28 of the blade is in particular adapted to aerodynamic requirements or to local de-icing requirements.

[0052] The body 28 may have an aerodynamic profile (leading and trailing edge, lower and upper surfaces), or it may be a strip of constant thickness.

[0053] The foot 30 is composed of a reinforcement 30.1 and an axis (or trunnion) 30.2. The head 32 is composed of a reinforcement 32.1 and an axis 32.2. The reinforcements 30.1, 32.1 and the axes 30.2, 32.2 are more rigid than the body 28. The axes 30.2, 32.2 are preferably coaxial about an axis A. The reinforcements 30.1, 32.1 are straight in this example.

[0054] The axes 30.2, 32.2 may have elements allowing them to be fixed in rotation with an actuator, such as for example a flat, a key, etc.

[0055] Figure 3 shows the blade 26 in a twisted configuration, that is, with the head 32 rotated by a given angle α about the axis A and the foot 30 rotated by an angle θ [3] relative to nominal angular positions. The twist can conventionally be the difference a-[3. Angles a and [3 can have different absolute values ​​and be of the same sign or opposite signs.

[0056] In other words, the blade 26 is not made of a profile only translated along the axis A.

[0057] This twist can be the nominal twist, that is to say the average twist representing a compromise for good motor efficiency at a given operating point. The nominal twist can be zero.

[0058] Figure 4 shows a variant for the blade, in which the armatures 30.1, 32.1 are discs. The discs can be partially or totally embedded in a housing provided for this purpose. The circular surface of the discs facing the blade allows for material continuity with the housing to guide the flow.

[0059] The embodiments of figures 3 and 4 can be combined: a blade can include a straight armature at one of its ends (head or foot) and a discoid armature at its other end.

[0060] Figure 5 partially represents a cross-sectional view of the air inlet 2 of a compressor 4 according to the invention. A housing 4.1 receives the various elements of the compressor and delimits an annular air channel 34.

[0061] The blade 26 is one blade among an annular row of blades 26. This blade 26 is arranged along an axis A substantially perpendicular to the direction of the airflow.

[0062] The foot 30 and the head 32 of the blade 26 are assembled on the housing 4.1 by means of actuators 36, 38 whose purpose is to rotate independently the foot 30 and the head 32.

[0063] The actuators 36, 38 are controlled by a control unit, for example, in communication with the FADEC. They impose a pivot angle on the head or the foot in order to obtain an orientation of the blade 26 and / or a twist of the blade 26. The orientation is the coordinated pivoting of the foot 30 and the head 32 (simultaneous angular displacement). The twist variations are obtained by a separate pivoting of the foot 30 and the head 32.

[0064] The actuators 36, 38 can be electric, such as stepper motors, directly driving each foot 30 and each head 32 of the blades 26.

[0065] The actuators 36, 38 can also be electric motors indirectly driving the blades 26 by means of a first ring simultaneously driving all the feet 30 of the blades 26 and a second ring simultaneously driving all the heads 32 of the blades 26.

[0066] The actuators 36, 38 can alternatively be based on known blade orientation mechanisms, i.e., with a ring pivoting a few degrees around the compressor axis under the influence of one or more cylinders, the crown being connected by respective connecting rods (or levers) to each blade 26. Thus, the rotation of the crown around the Z axis causes the rotation of the blade 26 around the A axis. In the present case where the foot 30 and the head 32 are independently controlled in pivoting, one crown can be provided to rotate the foot 30 of the blade 26 and another, independent crown can be provided to rotate the head 32 of the blade 26.

[0067] In order to impose oscillations or vibrations, an electric linear vibrator can be interposed between the ring and the connecting rods. The electric linear vibrator can be chosen to be transparent when inactive, i.e., not to create hysteresis during the pivoting of the blades.

[0068] The actuators 36 of the feet 30 can be of a different nature from those 38 of the heads 32.

[0069] The twisting as well as the setting of the orientation of the blade can be more or less accentuated (in particular between -10 and 60°), in particular depending on the engine speed.

[0070] The oscillations can be of different kinds and their amplitude and frequency can vary, in particular depending on the engine speed, the pressure, temperature and humidity conditions of the inlet flow, or even the orientation of the blade 26.

[0071] The technical features described above can be combined with each other in all possible technical combinations, unless otherwise explicitly stated.

[0072] If a preferred embodiment of the invention relates to a radial compressor, the same teachings are easily applicable to an axial compressor.

Claims

Demands

1. Aircraft turbomachine (1) compressor (4), the compressor (4) comprising: - a casing (4.1); - an inlet blade (26) having a foot (30) and a head (32), the foot and the head (32) defining between them a twist (a-[3] of the blade (26); and - a blade (26) orientation adjustment mechanism, the compressor (4) being characterized in that the blade (26) orientation adjustment mechanism comprises: - a first actuator (36) fixed to the casing (4.1), capable of pivoting the foot (30); and - a second actuator (38) fixed to the housing (4.1), capable of pivoting the head (32), said actuators (36, 38) allowing adjustment of the orientation of the blade (26), said actuators (36, 38) being configured to be controlled independently of each other in order to vary the twist (a-[3]) of the blade (26), and said actuators (36, 38) being arranged on either side of the blade (26).

2. Compressor (4) according to claim 1, characterized in that the foot (30) and the head (32) are each formed of a frame (30.1, 32.1) and an axle (30.2, 32.2), the frame (30.1, 32.1) and the axle (30.2, 32.2) being made of a more rigid material than the blade (26).

3. Compressor (4) according to the preceding claim, characterized in that the armature (30.1, 32.1) is a disc preferably embedded in the casing.

4. Compressor (4) according to any one of the preceding claims, characterized in that at least one of the actuators (36, 38) comprises an electric motor pivoting directly or indirectly the head (32) or the foot (30).

5. Compressor (4) according to any one of the preceding claims, characterized in that at least one of the actuators (36, 38) comprises a cylinder actuating a ring connected to the foot (30) or to the head (32) by a connecting rod.

6. Use of a compressor (4) according to any one of claims 1 to 5, comprising a step of varying the twist (a-[3] of the blade (26) by controlling at least one of the two actuators (36, 38), preferably depending on the rotation speed of the compressor (4).

7. Use of a compressor (4) according to any one of claims 1 to 5, comprising a step in which at least one of the actuators (36, 38) is controlled to create an oscillatory pivoting of the foot (30) and / or the head (32) of the blade (26).

8. Use according to claim 7, characterized in that the two actuators (36, 38) are controlled to oscillate the foot (30) and the head (32): - in phase, in opposite phase, with a phase shift or at different frequencies; and / or - with an identical or different angular amplitude; and / or - at a fixed or variable frequency, less than 0.5 Hz or greater than 10 Hz, depending on the compressor speed.

9. Use according to claim 7 or 8, characterized in that: - for certain regimes, in particular at low speed or idle or below a threshold regime, the oscillations are of large amplitude, for example about 1°, and of low frequency, for example less than 0.5 Hz; and / or - for certain regimes, in particular at high speed or above a threshold regime, the oscillations are of small amplitude, for example about 0.5°, and of high frequency, for example more than 10Hz.

10. Use according to any one of claims 7 to 9, characterized in that the oscillations are formed from a superposition of a large amplitude, low frequency oscillation, and a small amplitude, high frequency oscillation.

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